The present invention relates to a vibration-isolating device used to support a power unit such as a vehicle engine and other vibration generating sources for the purpose of vibration isolation.
A liquid-containing vibration isolator is taken as an example to describe a vibration-isolating device which supports a vibration generating source such as a car engine so as not to transmit its vibration to the vehicle body. The liquid-containing vibration isolator is typically configured so that a partition portion and a diaphragm are disposed inside the vibration-isolating device having a vibration-isolating substrate formed from a rubber elastomer and configured to constitute within the walls first and second liquid chambers which seal in liquid. These liquid chambers are connected by an orifice pathway, and the vibration damping function and the vibration isolating function are exhibited by the liquid flow effects of both liquid chambers by means of the orifice pathway and the vibration absorbing effects of the vibration isolating substrate. Various types of such vibration-isolating devices are known.
For example, in JP-A-132279/1999, a first attachment metal fitting embedded at the top center of the vibration-isolating substrate is vulcanization adhered, and a cylindrical metal fitting is vulcanization adhered at the outside of the lower part of the vibration isolating substrate. Then, the lower edge of the cylindrical metal fitting is sandwiched between an annular metal fitting, which retains the diaphragm, and the circumference of the partition portion and is caulked to the flange at the upper edge of a cylindrical second attachment metal fitting, this jig having a bottom. Furthermore, an L-shaped cross section stopper metal fitting is disposed to prevent the vibration-isolating substrate from excessively deforming. The stopper metal fitting is fixed to the cylindrical metal fitting by caulking the lower edge portion of the stopper metal fitting to the flange portion projecting outwardly from the upper edge of the cylindrical metal fitting, and carries out the stopper function when the lower surface of the upper edge horizontal portion of the stopper abuts the rubber layer on a part of the first attachment metal fitting.
On the one hand, in JP-A-38015/1998, the aforementioned L-cross section stopper fitting is annular and completely surrounds the vibration-isolating device.
The vibration-isolating devices described above are all configured to have a circular cross-section, taken perpendicular to the central axis. This is because a circular cross-section amenable to the manufacturing process. For example, when the stopper metal fitting described above is fitted by caulking operations, it is easy to produce the lower edge portion to be caulked and also perform caulking operations, allowing secure caulking operations without any problem even if the rotational position is slightly out of place.
However, when the vibration-isolating devices are configured in the form of a generally circle, useless space may be produced in the partition portion, depending on configuration of the partition""s orifice pathway for providing necessary vibrational damping or on the configuration of a second diaphragm or a third liquid chamber etc. in the partition portion.
In recent years, with the high demand for smaller automobiles and for freedom of design and engineering, installation space of the vibration-isolating device may be limited more than before, so it is important to achieve the vibrational damping performance required while holding down the size of the vibration-isolating device.
In view of the aforementioned problems, the present invention provides a vibration-isolating device equipped with stopper metal fittings to restrain excessive deformation which is capable of effectively making use of limited installation space and to which the stopper metal fittings are easily and securely assembled.
A liquid-containing vibration-isolating device of the present invention comprises a vibration-isolating substrate formed of a rubber elastomer, a first metal fitting connected to one side of the vibration-isolating substrate, a second cylindrical or annular metal fitting connected to the other side of the vibration-isolating substrate, a first stopper portion provided on the first metal fitting or a metal fitting connected to the first metal fitting, a flange portion projecting outwardly and provided on the second metal fitting or a metal fitting connected to the second metal fitting, a caulking portion to be caulked to at least a part of the above flange portion, and a stopper metal fitting having a second stopper portion close to the first stopper portion and disposed so as to be able to abut on the first stopper portion. The vibration-isolating substrate and the outer circumference of the second metal fitting trace an elliptical shape as viewed from the axial direction, and that at least the places where the outer edges of the caulking portion and the flange portion connect with each other are provided along the circumference of a circle around the central axis.
The aforementioned configuration allows the installation of the liquid-containing vibration-isolating device in a limited space which thus is effectively utilized, so that the accommodation of objects into automobiles is improved and the stopper metal fitting can be easily and securely assembled while optimizing the position of the stopper metal fitting around the central axis.
The elongated circle described above is made up of two equal semicircles and two straight lines smoothly connecting these semicircles, in the form of an oval typically seen in an athletic or race track.
Preferably, the caulked edges are disposed at the intersections of the elongated circle or the ellipse with its major axis, and the length of the flange in the direction of the minor axis of the elongated circle or the ellipse is smaller than the diameter of the axial cross section of the above circle around the central axis.
In these configurations, the limited installation space can be utilized more effectively.